Process and apparatus for dialyzing latex



Sept. 28, 1943. v

H. R-BRAAK PROCESS AND APPARATUS FOR DIALYZING LATEX Filed Nov. 19, 1940 Patented Sept. .28, 1943 PROCESS ,AND APPARATUS FOR DIALYZIN LATEX Hendrik Roelofl Braak, Batavia-Centrum, Java,

Netherlands East Indies, assignor, by mesne assignnients, to P. Honig, Washington, D. 0., Commissioner of the Board for Economic and Financial Affairs of The Netherlands Indies, Surinam and Curacao, as trustee Application November 19, 1940, Serial No. 366,306 In the Netherlands July 11, 1939 15 Claims.

"ably Cellophane hosing or tubes, water beingcaused to flow past the outside ofthe dialyzing elements.

At first fiat openreceptacles were used for this purpose, the dialyzing elements being horizontally deposited on the bottom of the said receptacles.

It appeared however that the Cellophane tubes deteriorated after a relatively short time of use. On investigation said deterioration appeared to be caused by the fact that the Cellophane tube is only resistant to hot alkali containing latex in .the absence of oxygen. As latex always foams somewhat a certain amount of air enters into the hosing in the foam, as well as being dissolved therein. This air accumulates in'the horizontal elements on certain points causing an accelerated local deterioration of the tubes. accumulation of air promotes the formationof lumps by coagulation of the latex. These lumps grow gradually bigger propagating themselves through the whole of the tube, until the latter finally gets clogged. This makes repeatedrenewal of the tubes necessary, causing undue expenses both on material and labor.

These drawbacks are obviated by the present invention. The invention consists therein that the latex is dialyzed, preferably at elevated temperatures, by causing the latex to flow through dialyzing' tubes, e. g. of seamless Cellophane, extending in substantially vertical direction, the tubes being connected, at the top part preferably, with air-discharge conduits which are open or can be opened.

According to the invention the dlalyzing hosing may e. g. be suspended in a number of receptacles or in a receptacle divided by means of partition walls into compartments, whereas the water is caused to flow through the different receptacles The invention will be further elucidated with the aid of the drawing wherein an apparatus according to the invention is represented by way of example, the application is however not restricted to this form of execution.

In the drawing, I is a receptacle wherein a number of dialyzing tubes 2, preferably of seamless Cellophane hosing are suspended. Thesetubes are connected at the bottom-side by closed,

U-shaped members 3 and at the top by open Y-shaped members 4. The latex, e. g. hot latex treated with alkali lye, according to the application, Serial No. 281,264 is fed to the apparatus through the inlet 5, flows through the tubes 2 and is removed through the discharge 6.

The receptacle l is divided by the partitions 1 into compartments through which, preferably, hot water flows, the water being supplied at 8 and discharged at 9. This water can moreover beheated, e. g. with the aid of live steam which is introduced through the bubbling discs Ill. The U-shaped connecting members 3, Y-shaped members 4, supply basin 5 and discharge basin 6 may be constructed of resistant material, e. g. of glazed china or alkali-resistant glass provided that the inner wall, which comes into contact with the latex, is sufllciently smooth to prevent coagulation. The Y-shaped members extend downward- 1y below the level of the hot water so that the Moreover local r -r compartments in a direction'substantially counter-current to that of the latex.

substantially vertically arranged Cellophane tubes, that is the Y-shaped members 4, enable the escape of the air which may have been introduced into the apparatus e. g. by dissolving in or by foaming of the latex, moreover lumps of coagulated rubber which may have been formed collect in the Y-shaped members in the top part of the apparatus so that obstruction of the dialyzing tubes is prevented. In the unusual case that a lump of coagulated rubber should adhere to the dialyzing wall and should grow bigger there it is possible to remove such a lump e. g. with the aid of a metallic rod or hook introduced through theopening in'the air-discharge conduit. This is, however, hardly ever necessary as generally the lumps rise of their own accord and adhere in the top part to the surface film formed in the Y member. If this film becomes too thick, it caneasily be removed. Since however air strong- 1y promotes coagulation of the latex, the provision made in this apparatus for the escape oi! alyzing cells is above the Cellophane membrane so that the latter does not come in contact with the air in the discharge conduits.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

What I claim is:

.1. In the purification of latex by'dialysis, the

process which comprises passing a latex containing dissolved and entrained air through dialyzing cells of tubular form having smooth, substantially vertical cell walls partly constructed of a semipermeable membrane leading directly upwardly to an air space above the level of said semi-permeable membrane and being free from obstructions tending to trap air beneath the surface of said latex, whereby all air liberated from said latex rises to enter said air space without collecting on said membrane, discharging the air thus collected from said air space and passing water through the apparatus in contact with said semi-permeable membrane outside said dialyzing cells.

2. In the purification of latex by dialysis, the process which comprises dialyzing latex, containing dissolved and entrained air and heated to a temperature tending to cause liberation of said air, through a dialyzing cell havingsmooth, substantially-vertical cell walls at least partly constructed of Cellophane leading directly upwardly without obstruction to an air space above the level of said Cellophane, whereby the air liberated from said latex rises into said air space without collecting on said cell walls, discharging the air thus collected from said air space and passing water through the apparatus in contact with said Cellophane outside said dialyzing cell.

3. In the purification of latex by dialysis, the process which comprises passing a latex containing dissolved and entrained air upwardly through a dialyzing cell, through an intermediate space and then downwardly through a second dialyzing cell, both of said dialyzing cells having smooth, substantially-vertical cell walls constructed at least partly of semi-permeable membrane, leading directly upwardly to said intermediate space and being free from obstructions tending to trap air beneath the surface of said latex, whereby all air liberated from the latex rises to enter said intermediate space without collecting on said cell walls, discharging-the air thus collected from said intermediate space and passingiwater through the apparatus in contact with said semi-permeable membrane outside said dialyzing cells.

4. The process of claim 3 wherein the latex is heated while passing through said dialyzing cells to temperatures causing liberation of the dissolved and entrained air from said latex.

5. In the purification of latex by dialysis, the process which comprises dialyzing a latex containing dissolved and entrained air while passing it through a cylindrical dialyzing cell having a substantially vertical wall partly constructed of Cellophane, the upper portion of said wall forming an air spac above the Cellophane, whereby the air liberated in said cell risesinto said air space without collecting on the cell walls and the Cellophane is protected from contact with air and passing water through the apparatus in con tact with said Cellophane outside said dialyzing cell.

6. An apparatus for dialyzing latex comprising in combination a dialyzing cell of tubular form having smooth, substantially-vertical walls of a semi-permeable membrane and an air-discharge conduit adapted to discharge air liberated from the latex passed through said cell and to conduct said latex from said cell to another dialyzing cell, said discharge conduit having smooth, substantially-vertical walls merging with said vertical membrane walls without substantial obstruction, whereby any air liberated from said latex rises into said air-discharge conduit without collecting on, said membrane and means for passing water through the apparatus in contact with said semipermeable membrane outside dialyzing cell.

7. An apparatus for dialyzing latex comprising in combination at least two dialyzing cells and an intermediate air-discharge conduit adapted to discharge air liberated from the latex passed through said cells and to conduct said latex from the top of one cell to the top of the other, said cells having smooth, substantially-vertical walls of a semi-permeable membrane leading directly upwardly into said conduit, said conduit having smooth, substantially vertical walls of resistant material merging with the vertical walls of both cells without substantial obstruction, whereby any air liberated from said latex rises and passes into said conduit without collecting on said cell walls and means for passing water through the apparatus in contact with said semi-permeable membrane outside said dialyzing cells.

8. The apparatus of claim 7 wherein said dialyzing cells are substantially cylindrical in shape while said air discharg conduit is Y-shaped.

9. The apparatus of claim 7 comprising a plurality of dialyzing cells connected in series, the tops being connected together by said air discharge conduits and the bottoms being connected by closed connecting members.

10. The apparatus of claim 1 comprising a plurality of dialyzing cells of substantially cylindrical shape connected in series, the tops being connected together by substantially Y-shaped airdischarge conduits and the bottom being connected by closed, substantially U-shaped members.

11. The apparatus of claim 7 wherein said semi-permeable membrane is of Cellophane hosing.

12. An apparatus for dialyzing latex comprising in combination a receptacle, partition walls dividing said receptacle into a plurality of compartments connected with each other at the top and at the bottom parts oi the partition walls.

dialyzing cells of tubular form mounted in said compartments having smooth, substantially vertical cell walls of a semi-permeable membrane, air-discharge conduits of resistant material connecting said cells at their tops and adapted to discharge air from said cells and to conduct the latex from the top of one cell to the top of the next seriatim, said air-discharge conduits being provided with smooth, substantially vertical walls merging with the vertical walls of said cells without substantial obstruction, whereby any air liberated from said latex rises into said air-discharge conduits and is discharged therefrom without collecting onthe cell walls, closed connecting members for conducting the latex from the bottom of one cell to the bottom of the next sertatim, means for passing latex through said cells, and means for passing water through said compartments in contact with the outersurtace of said semi-permeable membranes and in counter-cur- 1o rent to said latex.

13. The dialyzing apparatus of claim 12 wherein said semi-permeable membrane is of Cellophane.

14. The dialyzing apparatus of claim 12 where- 15 in means are provided for introducing live steam into the bottom of the receptacle for heating the latex and water therein. 1

15. An apparatus for dialyzine latex which comprises a receptacle, means for passing water Cellophane without substantial obstruction, whereby the air liberated in said cells and lumps of coagulated matter rise and collect in said memhere without collecting on the cell walls, said members having an opening at the top permitting escape of said air and removal of said coasulated matter, and means for passing latex throuzh said dialyzin: cells.

HENDRIK ROELOFF BRAAK. 

